1. Field of the Invention
The invention relates to the field of orthopedics, and more particularly to a bone pin for the coupling of two separate pieces of bone together for use in the surgical correction of hammer toe.
2. Description of the Prior Art
One surgical method of treatment of hammertoe involves the surgical implantation of bone pins, and more particularly, an interphalangeal fusion pin which provides an anatomically correct angle between a first phalange and a second phalange, such as the proximal phalange and the intermediate phalange which exists at the proximal interphalangeal joint, wherein the pin is comprised of a resorbable or permanent material.
Digital deformities of the fingers and toes are some of the most common conditions encountered by orthopedists and podiatrists. Patients with digital deformities often experience significant pain from structural abnormalities. Some of these abnormalities are acquired, caused by traumatic injuries, neuromuscular pathologies, systemic diseases, or mechanical problems secondary to extrinsic pressures. The deformities are popularly known as either mallet finger, jersey finger, coach's finger, hammer toe, as well as a host of others indicative of several different pathologies.
Hammer toe is generally described in the medical literature as an acquired disorder, typically characterized by hyperextension of the metatarsophalangeal joint (MTPJ), hyperflexion of the proximal interphalangeal joint (PIPJ), and hyperextension of the distal interphalangeal joint (DIPJ). Although this condition can be conservatively managed (e.g., through the use of orthotic devices), in certain instances surgical intervention is required.
In order to prevent recurrence of the deformity and ensure the success of the surgical procedure, a proximal interphalangeal (PIP) joint arthrodesis is typically performed. The “end-to-end” or “peg-in-hole” techniques are the most commonly used procedures. The PIPJ is aligned with the rest of the toe in a corrected anatomical position and maintained in place by the use of a 0.045 Kirschner wire (K-wire) which is driven across the joint. Initially, the wire is placed from the PIPJ through the tip of the toe. It is then driven in retrograde fashion into the proximal phalanx. The exposed wire exiting the toe is bent to an angle greater than 90 degrees, and the bent portion is cut at 1 cm from the bend. At the conclusion of the surgical procedure, a small compressive dressing is placed around the toe, with a Jones compression splint being used for three to four weeks to protect the pin and the toe in order to maintain correction. The K-wire and the Jones splint are generally removed three weeks after surgery. Similar procedures may be followed to create arthrodesis of the distal interphalangeal joint (DIP) of the toe or for arthrodesis performed in the finger to correct digital abnormalities of the hand.
Although this type of surgical procedure has alleviated the discomfort of hammer toe and other abnormalities of the toe and finger joints for countless patients, the use of K-wire can result in the possible post-surgical misalignment of the phalanges (e.g., caused by distraction of the K-wire), as well as swelling, inflammation, and possible infection at the site of the exposed K-wire segment.
Of recent interest in the treatment of toe deformities, such as hammer toe, are prosthetic devices which have been used to treat deformities of the finger joints. For example, these devices can be inserted into adjoining phalanges of the finger and can serve to function ostensibly as a normal knuckle would. Because it is generally necessary to permit one or more of the joints of the finger to flex and bend, some of these devices are slightly angled to provide for an anatomically acceptable interphalangeal joint angle of the finger. Furthermore, some of these devices allow the joint portion to bend to a significant degree, thus permitting the finger a relatively wide range of articulation.
These devices are typically comprised of metallic or thermoplastic materials which, while being biocompatible, are also physiologically inert and thus are not resorbed by the body. There are, however, conditions in which an arthrodesis, or fusing of the affected finger or toe joint is desired, making a permanent device which is designed to permit joint flexion/extension inappropriate. Thus, the use of these permanent prosthetic devices in the treatment of hammer toe and other digital deformities, wherein the goal of the operation is arthrodesis, whereby the presence of the device would only be required for a short number of weeks to aid in maintaining correct anatomical alignment of the phalanges for fusion, would not be indicated. Additionally, these permanent devices would also be contraindicated in the treatment of certain finger conditions where the phalanges need to be correctly anatomically aligned for only a few weeks until a proper amount of healing for fusion has occurred.